The European Union's senior envoy to Afghanistan says the NATO-led drive to secure the south of the country must succeed. The EU diplomat warned that failure to defeat Taleban insurgents could result in the country once again becoming a major haven for terrorists.

The special EU representative for Afghanistan, Francesc Vendrell, briefed reporters in the capital, Kabul.

The veteran Spanish diplomat warned terrorist groups in the region could still regain a foothold in Afghanistan.

"This is why NATO cannot fail in the south," Vendrell said. "We are not going to tolerate any kind of haven for terrorist elements in Afghanistan and on this we will stay here for as long as it takes to get this issue resolved."